This invention relates to irrigators, and in particular it relates to travelling irrigators having only one irrigation arm moving in oscillating reciprocal motion. The irrigators of the invention are particularly suitable as travelling irrigators of the kind that are mounted on wheels and drawn by means of a fixed cable over a field or paddock.
A large variety of irrigators, and particularly travelling irrigators are known. The traditional travelling irrigator, generally used to supply effluent from dairy milking sheds to nearby pasture or crop land, has two arms which are rotated by the forces generated by the discharge jet of irrigating liquid in each arm. The rotating arms are usually linked to a winch which winds up a cable attached to a distant, fixed post. The tension in the cable created as it is wound in by the winch, causes the irrigator to be pulled along the paddock being irrigated, and the liquid supply hose, being attached to the irrigator, is pulled along the paddock. As the two arms of the irrigator rotate constantly in one directly they therefore need to be connected to the supply hose by means of a mechanism which enables the rotation without winding up or twisting the supply hose. Traditionally a rotary gland is provided for this purpose, which contains of necessity, seals and rubbing parts which are immersed in the irrigating liquid. It is desirable to use milking shed effluent or the like as the source of irrigating liquid and this liquid usually contains a high percentage of sand and grit which subjects the glands to high wear and tear. It is therefore desirable to be able to provide an irrigator which can dispense with the need for a gland or the like.
Furthermore, in the traditional two-arm irrigators two nozzles are operating simultaneously. If all the liquid being pumped through the two nozzles was directed through a single nozzle it would have almost double the range or carry for the same pumping effort and therefore be distributed over nearly twice the area. Furthermore a single larger nozzle would be less likely to become clogged with grit, sand or other particulate matter in the irrigating liquid.
A further potential advantage of an irrigator employing only one arm and one nozzle is in the regularity with which it must be shifted. The two arm irrigators need to be shifted every seven to ten days. However, a single arm irrigator, with the ability to distribute liquid over approximately twice the area, would only need to be shifted every fourteen to twenty days. As there is a large amount of effort involved in shifting these irrigators this represents a considerable advantage to the farmer.
There is therefore an advantage in providing an irrigating apparatus which can extend the area over which liquid can be distributed and eliminate the need for complex moving parts within the apparatus.
It is an object of the invention to provide an improved apparatus for the irrigation of large areas of farmland and the like, or at least to provide the public with a useful choice.
It is another object of the invention to provide an improved method for the irrigation of large areas of farmland and the like or at least to provide the public with a useful choice.
In one aspect the invention provides an irrigator including a single irrigation arm said arm adapted to move in reciprocal rotational motion by in a first setting spraying irrigating liquid at a first orientation with respect to the arm to move the arm in a first direction and in a second setting spraying irrigating liquid at a second orientation with respect to the arm to effect a reversal in the rotational direction of the arm, and including means to alter the arm from said first to second settings.
Preferably the irrigation arm has at least one nozzle set at a fixed angle with respect to the arm so that in a first setting of the arm the emerging irrigation liquid causes the arm to rotate in a first direction, and means to effect a rotation of the arm through substantially 90xc2x0 about its longitudinal axis at the end of each rotational arc to a second setting in which the emerging irrigation liquid causes the arm to rotate in the reverse direction.
Preferably a rocker arm is attached to the irrigation arm and in a first position is in contact with a first actuator which is adapted to be activated at the end of a first rotational arc of the irrigation arm in a first direction and on activation causes the rocker arm to rotate through substantially 90xc2x0 to a second position in contact with a second actuator and simultaneously effecting a rotation of the irrigation arm through substantially 90xc2x0 about its longitudinal axis to thus cause the arm to move in a second or reverse direction, said second actuator being similarly adapted to be activated at the end of the rotational arc of the irrigation arm in the second direction.
Optionally the irrigator arm is fitted with at least one nozzle, adapted to move from a first to a second position with respect to the arm at the end of each rotational arc of the arm.
Preferably the the inner end of the irrigation arm is connected to a flexible hose through which the irrigating liquid is delivered.
Preferably the irrigator arm rotates through about 180xc2x0 before the rotational direction is reversed.
Preferably the irrigator is fitted with wheels and the reciprocating motion of the irrigation arm is converted to a unidirectional motion for the purpose of activating driving means to wind in a cable attached at a first end to the winding means located on the irrigator and at a second end to a fixed point outside the irrigator such that as the cable is wound in by the motion of the irrigator arm the irrigator is moved over the terrain to be irrigated.
Preferably the winding means includes a drive shaft upon which a capstan drum including at least one self-tailing sheave and at least one active sheave is fixedly mounted and an idler shaft on which at least one idler sheave is rotatably mounted is in combination with a cable guide fixedly mounted to a rotating guide shaft positioned substantially centrally with respect to a cable container so that as the cable leaves the self-tailing sheave of the winding apparatus it passes through the cable guide and as the guide shaft rotates the cable is laid into the cable container.
Optionally the winding mechanism is a winch in combination with a cable reel.
In another aspect the invention provides an apparatus for irrigation including a single irrigation arm attached at its inner end to a hose means providing the irrigating liquid to the said arm and adapted to enable repeated oscillating rotational motion of the arm, and provided at its outer end with nozzle means positioned to direct the stream of emerging irrigating liquid at a first angle with respect to said arm such that the force of the emerging liquid causes the arm to rotate in a first direction, and at the end point of the said first rotation to effect a reversal in the rotational direction of the said arm by altering the position of the nozzle relative to the arm to direct the stream of the emerging liquid at a second angle with respect to the said arm, and repeating said reversal at the end of each rotational swing of the arm.
Preferably the hose means consists of at least a segment of the hose being formed from a hosing material so constructed as to have a greatly reduced tortional resistance.
Alternatively the hose means consists of one or more coils of hose which can repeatedly tighten or loosen as the arm oscillates between the first and reverse directions.
Preferably the arm is counterbalanced. When the irrigator moves over an inclined surface the solitary arm is subject to gravitational force and would tend to rotate to a neutral position. Preferably therefore the arm would be fitted with a counterbalance to prevent this from happening. The counterbalance could be formed from a hollow tube which fills with liquid when the irrigator begins to operate, and which exactly counterbalances the single arm when full. However, any suitable method of counterbalancing the arm is envisaged as being within the scope of the invention.
In another aspect the invention provides a method of irrigating comprising connecting an irrigator including a single irrigation arm said arm adapted to move in reciprocal rotational motion by in a first setting spraying irrigating liquid at a first orientation with respect to the arm to move the arm in a first direction and in a second setting spraying irrigating liquid at a second orientation with respect to the arm to effect a reversal in the rotational direction of the arm, and including means to alter the arm from said first to second settings, to a source of irrigation liquid at a sufficient pressure to activate the irrigation arm, and causing the liquid to flow through the irrigation arm.
In yet another aspect the invention provides a method of irrigation comprising the steps of connecting an apparatus including a single irrigation arm attached at its inner end to hose means providing the irrigating liquid to the said arm and adapted to enable repeated oscillating rotational motion of the arm, and provided at its outer end with nozzle means positioned to direct the stream of emerging irrigating liquid at a first angle with respect to said arm such that the force of the emerging liquid causes the arm to rotate in a first direction and at the end point of the said first rotation to effect a reversal in the rotational direction of the said arm by altering the position of the nozzle relative to the arm to direct the stream of the emerging liquid at a second angle with respect to the said arm, and repeating said reversal at the end of each rotational swing by the arm, to a source of a liquid for irrigation, and spraying said liquid over the areas to be irrigated.
Preferably the irrigating liquid is the effluent liquid from a cow milking shed or the like.
Alternatively the irrigating liquid is water.
The invention will now be described in detail by way of some preferred embodiments. However, it will be appreciated that variations, modifications and additions may be made on these embodiments without departing from the scope of the invention.